This is my first-time building a system.

Antec SLK1650 retail case with 350 watt power supply.

Here is a list of everything plugged into the motherboard:
Shuttle AN35N-Ultra motherboard
Athlon AMD XP 2500 1.83 Ghz CPU
1 GB RAM
ATI Radeon 9600 AGP video card
2 hard disk drives (1 Maxtor & 1 Western Digital)
Memorex 48MAXX 148AJ CD-RW drive.
HP DVD300I DVD+RW drive
3 cooling fans (front/side/rear).

Running Windows XP Professional.

I was getting "SCSI Command Aborted" and "Power Calibration Error" messages
in Nero when trying to burn DVD or CD on one of my two drives. Built-in XP
burning software reported errors as well. Someone suggested that my power
supply wasn't robust enough and that I should unplug a peripheral. Sure
enough, if I unplug my CD-RW I can get the DVD+R to burn just fine. Plug the
CD-RW back in and wham! the problem returns like clockwork.

My setup is very basic, and I find it really hard to believe that I am
pushing or exceeding the limits of a 350-watt power supply. Not to mention,
I was getting the burning error messges when I had only one cooling fan
running (before installation of the two auxilary fans).

Another possibly-related problem is this: if I try to connect one or both of
my two auxilary fans directly to the motherboard with those 3-pin
connectors, I cannot get power to the motherboard. I hit the switch and the
power comes on and quickly shuts down. If, however, I connect the fan to a
4-pin connector directly to the power supply and NOT to the motherboard
itself, the fans work fine and I can get power to the motherboard.

Please advise. Is my power supply inherently the issue or am I maybe dealing
with a defective one? Is it something else entirely?